package kingim.utils;

import java.util.Map;

import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/**
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候中取出ApplicaitonContext.
 */
public class SpringContextHolder implements ApplicationContextAware
{

    private static ApplicationContext applicationContext;

    // 实现ApplicationContextAware接口的context注入函数, 将其存入静态变量.
    public void setApplicationContext(ApplicationContext applicationContext)
    {
        SpringContextHolder.applicationContext = applicationContext;
    }

    // 取得存储在静态变量中的ApplicationContext.
    public static ApplicationContext getApplicationContext()
    {
        checkApplicationContext();
        return applicationContext;
    }

    // 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型.
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name)
    {
        checkApplicationContext();
        return (T)applicationContext.getBean(name);
    }

    // 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型.
    // 如果有多个Bean符合Class, 取出第一个.
    @SuppressWarnings("unchecked")
    public static <T> T getBean(Class<T> clazz)
    {
        checkApplicationContext();
        @SuppressWarnings("rawtypes")
        Map beanMaps = applicationContext.getBeansOfType(clazz);
        if (beanMaps != null && !beanMaps.isEmpty())
        {
            return (T)beanMaps.values().iterator().next();
        }
        else
        {
            return null;
        }
    }

    private static void checkApplicationContext()
    {
        if (applicationContext == null)
        {
            throw new IllegalStateException(
                "applicaitonContext未注入,请在spring.xml中定义SpringContextHolder");
        }
    }

}
